Photodynamic cytotoxicity in SNP cells. The cells were incubated with various concentrations of (a) mono-L-aspartyl chlorin e6 (NPe6) and (b) glucose-conjugated chlorin e6 (G-Ce6) for 24 h at 37 °C. After washing with fresh media, the cells were irradiated with 650-nm laser light (10 mW/cm2; 0, 1, 5, and 15 J/cm2). The viability of SNP cells at 24 h after photodynamic therapy, along with IC50 values, were determined. (a) The IC50 values of NPe6 at light doses of 1, 5, and 15 J/cm2 were 75.2, 30.4, and 30.6 μg/mL, respectively. (b) The IC50 values of G-Ce6 at light doses of 1, 5, and 15 J/cm2 were 33.4, 10.4, and 1.7 μg/mL, respectively. IC50, half-maximal inhibitory concentration. Results are presented as the mean ± standard deviation.